Thoughts on two subjects, cylinders with .080" bore, crank with counter weights

[RGould1910]

I'd appreciate thoughts on two subjects. I am restoring a 27 engine that sat for a lot of years. It was restored about 40 years ago and driven sparingly for about 10 years. My issues are the benefits and detriments of two items I found on disassembly. The crank has counter weights bolted on. It appears they have been drilled for balance. So has the flywheel. Don't know whether they were static or spin balanced. Also the cylinders have been bored .080".
I'd like to hear thoughts from those who have run counter weights,and those who have bored blocks .080" OS, pro and con. Thanks in advance for any input.

[RGould1910]

Forgot to add the crank has been turned .025" under. Rods are .020" under.

[Nv Bob]

Richard long time my friend
I seen bolted counter weights come loose not pretty but when working they do make for a smoother engine
.080 bore can be had but if the holes are that big time to think to sleeve them. Yes you can get away with if

[Henry K. Lee]

Richard,

Those style like the Dunn ones are very good but the real secret is tack welding the end of the threads pass the nuts. The use of a nickel alloy rod to attach them slightly to the crankshaft is an added bonus. Been doing it for about 20 years with no issues. Just me.

Hope this Helps,

Hank

[Les Schubert]

I have had the bolt on Dunn weights on my 27 roadster since 1979 and many thousands of miles. If these are still hanging in there, I would not be too concerned. The weld spot is probably OK. I would carefully loosen the bolts one at a time, being careful not to disturb the fit up, and put some Loktite on the threads and retorque to the way they are. Yours might have cotter pins and if so, don’t touch it!!!!
If it was my engine and I had it apart I would get the crank and flywheel dynamically balanced while it is convenient.
The.080 wouldn’t bother me if there is no sign of coolant “weepage “
Best of luck

[henryford2]

Just an FYI my experience with the "new aftermarket bolt on counterweights especially on the 26/27 crank was they had to be "fitted" to the crank, otherwise they will put a "bend" in the crankshaft. Used grade 8 bolts, locking nuts and thread locker. Ultimately decided against using them.

[Les Schubert]

A few more thoughts;
1. Check the crank for deflection at the centre main bearing. Remove the centre main cap and check for wear in this bearing. Some wear in the centre main is not unusual. Now take a dial indicator and have it run on the centre main as you turn the crank. I would hope for very little runout. Perhaps.002-.003 max. A poor installation of the bolt on weights will cause significant bend in the crank. I have witnessed it!!
2. .080” over bore. As long as there is no evidence of coolant leakage into the cylinder bores, then I would have no concern.
IF there was evidence of leakage then a sleeve job and smaller pistons is a perfectly reasonable solution. I have sleeved T blocks back to standard several times

[RGould1910]

Thanks to all responders for all the helpful suggestions. I don' know where else you can get all this collective input.

[Joe Bell]

Richard, I had two engines done by some one else that came in with a bad mid range vibration, after opening them up both had the counter weights attached. They had been balanced with the weights to the crank and spot welded to the crank. I sent them out for Dynamic balancing reinstalled the crank fired it up and the vibration was still there?? I do not know if the weights where original early style or later repops? I removed the weights and rebalanced and the vibration was gone?? The owner was happier than a pig in slop after it was redone this way. This was my first issue with them attached like this and since then I really do not care for them. Just what I had found on a couple engines, hope this helps.
Thanks Joe

[Joe Bell]

Richard, I had two engines done by some one else that came in with a bad mid range vibration, after opening them up both had the counter weights attached. They had been balanced with the weights to the crank and spot welded to the crank. I sent them out for Dynamic balancing reinstalled the crank fired it up and the vibration was still there?? I do not know if the weights where original early style or later repops? I removed the weights and rebalanced and the vibration was gone?? The owner was happier than a pig in slop after it was redone this way. This was my first issue with them attached like this and since then I really do not care for them. Just what I had found on a couple engines, hope this helps.
Thanks Joe